Large water filtration systems frequently include one or more stages of filtration that clean the influent (typically water) to a sufficient level to allow for the discharge of the influent into a natural body of water such as a lake or river. In regions where water is scarce, it may be desirable to further filter the water to allow for “reuse” of the water.
Many wastewater treatment plants utilize a disc filter system to filter water. Such systems typically include a plurality of discs each including a plurality of filter segments. Each filter segment includes a pair of filter panels which are spaced apart and arranged on an outer surface of the drum. A cap is attached to the top of each pair of filter panels to thus form a pocket shaped filter segment for receiving water. Each filter panel includes filter media, such as finely woven cloth for filtering water.
Each filter panel is attached to the drum by a filter support arrangement. Each filter support includes a plurality of support openings which provide fluid communication between adjacent filter segments. This enables water and air to flow circumferentially between adjacent filter segments as the drum rotates, thus resulting in an increase in capacity of the disc filter system.
In operation, the drum is rotated and the water to be filtered is introduced into the drum. The water then exits through ducts in the drum and flows into filter segments inside the filter support The water in the filter support is then filtered through the media of the filter panels to provide filtered water. The filtered water is then collected in a chamber and exits the disc filter through an effluent pipe. Particulates which are filtered out by the filter panels remain within the filter segments on the inside surface of the filter media of the filter panels. A spray device is used to spray the panels with water to dislodge the particulates and clean the filter media. The particulates are then collected onto a trough and are removed from the disc filter system.
The drum ducts used in conventional systems are of sufficient size to allow large rags, weeds, algae, fibrous assemblages and other trash to pass through unimpeded. By way of example, the ducts may be approximately 4-8 square inches in area. By contrast, the total area of the support openings between filter segments is substantially smaller and may be in the range of approximately 1 square inch. During operation, trash is able to pass through the drum ducts but may not readily pass through the smaller support openings. As a result, trash accumulates at the support openings between filter segments which then causes the support openings to become either partially or completely blocked, thus impeding or stopping the flow of water between adjacent filter segments. This results in turbulent flow inside the filter segments, reducing the flow of particulates into the capture trough, thus increasing operating costs. Further, the support openings cannot be effectively reached and thus cleaned by current spray devices, necessitating frequent stoppages of the disc filter system to allow for manual cleaning of the system in order to maintain operating effectiveness. Therefore, it is desirable to provide a disc filter system in which the amount of trash collected at the support openings is substantially reduced.